Hi,
You can't do it with a free shipping method since it can only apply per warehouse.
In that case, instead of a free shipping method, you can create a coupon via the Orders>Coupons menu.
Set its "shipping percentage" to 100%, activate its "auto load in cart if possible" setting so that it will apply to the cart automatically when necessary, and enter 5000 in the "Order value from" setting.
The coupon condition will be on the total amount, and the 100% shipping percentage value will be calculated on the total shipping fee.
This way, it will work the way you want.
The only drawback with this solution is that if the free shipping coupon is applied, the customer cannot add another coupon to the cart to get an extra discount on his order.
If that's something you need, you could use the multicoupon plugin to allow for several coupons to be usable:
www.hikashop.com/marketplace/product/164...coupon-checkout.html
Or, you could also use the cart fee plugin instead of a free shipping auto loaded coupon:
www.hikashop.com/marketplace/product/279-cart-fee.html
With it, you can have a formula with a condition to trigger an extra discount which can be based on the total shipping fee and conditioned to the total amount of the cart.